Ductwork is often used to convey conditioned air (e.g., heated, cooled, filtered, humidified, dehumidified, etc.) discharged from a fan and to distribute the air to a room or other areas within a building. Ducts are typically formed of generally self-supporting sheet metal, such as steel, aluminum, or stainless steel. Some ducts, however, are made of pliable materials, such as fabric or flexible plastic sheeting.
Pliable ducts are often suspended from a horizontal cable or track by way of a series of connectors distributed along the length of the duct. The connectors may include snap-hooks, clips, rings, or other type of connector that can slide along the cable or track. The connectors preferably allow the fabric duct to be readily removed from its cable or track so that the fabric duct can be cleaned.
When a fan or blower forces air through a pliable duct to supply the room with air, the pressure of the forced air tends to inflate the duct. This can cause the duct to expand radially and longitudinally to a generally cylindrical shape. When the ventilating or other conditioning demand of the room is satisfied, the blower is usually turned off, which allows the duct to deflate and retract lengthwise.